The present invention relates to video systems employing chopped, thermal detectors, and more particularly, to perceptual image difference or delta frame processing for use with such video systems.
Conventional image difference and delta frame processing techniques employed in video systems store each image frame and subtract it from the subsequent image frame to produce a difference signal .DELTA.s given by: .DELTA.s=2[(-1).sup.(N+1) -(-1).sup.N ].beta..DELTA.T=2(-1).sup.N .beta..DELTA.T. In this equation N is the frame number, and .beta..DELTA.T is a signal that is proportional to the temperature difference between the scene and a chopper blade used in the conventional video system, and is given by the equation [.beta..times..DELTA.T(chopper-scene)]. The conventional video systems alternate the sign of the difference signal .DELTA.s to produce a final result, comprising a video signal that is provided to a video display for viewing.
Typical of such conventional video systems employing image difference and delta flame processing are systems described in "Improved Performance from PyroElectric Vidicons by Image-Difference Processing", IEEE Symp. on Appl. of FerroElectrics, June 1975, and U.S. Pat. No. 4,178,612 entitled "Delta Frame Circuit" issued to Dudley et at.
It is therefore an objective of the present invention to provide a system and method for use with chopped, thermal detectors, and the like, that provides the same performance benefits as image difference or delta frame processing.